Multi-RF Impedance Control for Plasma Uniformity
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Solution Overview
Problem
Current plasma processing systems for semiconductor wafer fabrication face challenges in achieving uniform plasma and etching conditions due to inadequate control over ion energy and plasma chemistry, leading to non-uniform deposition and etching on wafers.
Innovation Solution
A wafer processing apparatus utilizing multiple radio frequency (RF) power sources and resonant circuits to control plasma density and chemistry, allowing for independent adjustment of RF power frequencies and impedance to ensure uniformity in plasma and etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single plasma is controlled to achieve radical separation, radical flux, ion energy, and ion flux, then plasma processing conditions are established, but uniformity in plasma and etching is insufficient due to coupled chemistry dissociation and ion production
Solution Approach 1:
The patent divides the plasma control into separate independent plasma sources: one plasma source for generating radicals and another for generating ions. This segmentation allows independent control of chemistry dissociation and ion production, resolving the coupling problem that limited uniformity control in single-plasma systems.
Solution Approach 2:
The patent introduces a grid electrode as an intermediary component between the top and bottom electrodes. This grid electrode enables independent control of plasma parameters by allowing separate biasing of the two plasma sources, facilitating precise control over ion energy and radical flux independently.
2Manufacturing precision
If controls are inadequate for ion energy and plasma chemistry, then processing equipment can be used in wide range of applications, but non-uniform deposition and etching result on the wafer
Solution Approach 1:
By segmenting the plasma generation into two independent sources with separate control circuits, the system achieves precise control over multiple plasma parameters simultaneously. The dual-plasma architecture with independent control of each source enables uniform processing while maintaining manageable system complexity through modular design.
3Reliability
If chemistry dissociation and radical formation are coupled to ion production in a single plasma, then plasma is generated efficiently, but desired plasma processing conditions cannot be achieved due to lack of independent control
Solution Approach 1:
The patent implements segmentation by creating two spatially separated plasma regions: one optimized for radical generation and another for ion generation. Each plasma source can be independently controlled in terms of power, gas flow, and electrode biasing, enabling reliable achievement of desired processing conditions with full adaptability.
Solution Approach 2:
The patent applies local quality by creating different plasma conditions in different spatial regions. The top plasma source region is optimized for radical production while the bottom plasma source region is optimized for ion production, allowing each region to have the specific properties needed for its function while maintaining overall system reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides improved uniformity in plasma and etching across the wafer surface, enabling precise control over plasma chemistry and etching rates, thereby enhancing the manufacturing process for semiconductor wafers.
Implementation Method 1
Each of the one or more resonant circuits resonate at one of the frequencies of the RF power sources coupled to the bottom electrode
Implementation Method 2
a first radio frequency (RF) power source, a second RF power source, a third RF power source, a fourth RF power source... to provide plasma and etching uniformity for the wafer
Data Source
AI summary
Circuits, methods, chambers, systems, and computer programs are presented for processing wafers. A wafer processing apparatus includes top and bottom electrodes inside a processing chamber; a first, second, third, and fourth radio frequency (RF) power sources; and one or more resonant circuits. The first, second, and third RF power sources are coupled to the bottom electrode. The top electrode may be coupled to the fourth RF power source, to electrical ground, or to the one or more resonant circuits. Each of the one or more resonant circuits, which are coupled between the top electrode and electrical ground, include a tune-in element operable to vary a frequency-dependent impedance presented by the resonant circuit. The wafer processing apparatus is configurable to select the RF power sources for wafer processing operations, as well as the connections to the top electrode in order to provide plasma and etching uniformity for the wafer.